Silicon photonics is a technology for integrating silicon-made large-scale integrated circuits (LSIs) and silicon optical semiconductor components, and has recently attracted much attention. In related art LSI technologies, data transfer both between and within central processing units (CPUs) or microchips is performed by using interconnects made of metal such as Cu. In contrast, silicon photonics technology enables optical signal transmission to provide faster, less energy-consuming data transfer between and within CPUs.
In silicon photonics technology, an optical waveguide 920 made of silicon is formed on a surface of a silicon substrate, and a semiconductor laser light source 930 serving as a light source is mounted on the silicon substrate, as illustrated in FIG. 1. As a semiconductor laser light source 930, a compound semiconductor laser is generally used; a quantum-well laser is an example of the compound semiconductor laser. The semiconductor laser light source 930 is directly coupled to the optical waveguide 920 with high coupling efficiency to form a spot size converter to convert a spot size of a laser beam to the enlarged spot size, for example, of approximately 3 μm.
However, in the case of the quantum well laser, the oscillation threshold and the drive current are liable to vary with an environmental temperature of the place on which the semiconductor laser light source 93C is mounted. Specifically, when a CPU or the like is installed in a silicon photonics device, the amount of heat generated by the CPU or the like is large, and heat generated from the CPU or the like is transmitted through the silicon substrate or the like, which makes the environmental temperature high. Thus, it is not preferable to employ the silicon quantum well laser as a light source in a silicon photonics device, because the use of the silicon quantum well laser may change characteristics such as an oscillation threshold and a drive current of the laser, which may result in high energy consumption or failing to provide desired characteristics.